Oxygen bleaching agents have become increasingly popular in recent years in household and personal care products to facilitate stain and soil removal. Bleaches are particularly desirable for their stain-removing, dingy fabric cleanup, whitening and sanitization properties. Oxygen bleaching agents have found particular acceptance in laundry products such as detergents, in automatic dishwashing products and in hard surface cleansers. Oxygen bleaching agents, however, are somewhat limited in their effectiveness. Some frequently encountered disadvantages include their lack of fabric color safety and their tendancy to be extremely temperature rate dependent. Thus, the colder the solution in which they are employed, the less effective the bleaching action. Temperatures in excess of 60° C. are typically required for effectiveness of an oxygen bleaching agent in solution.
To solve the aforementioned temperature rate dependency, a class of compounds known as “bleach activators” has been developed. Bleach activators, typically perhydrolyzable acyl compounds having a leaving group such as oxybenzenesulfonate, react with the active oxygen group, typically hydrogen peroxide or its anion, to form a more effective peroxyacid oxidant. It is the peroxyacid compound which then oxidizes the stained or soiled substrate material. However, bleach activators are also somewhat temperature dependent. Bleach activators are more effective at warm water temperatures of from about 40° C. to about 60° C. In water temperatures of less than about 40° C., the peroxyacid compound loses some of its bleaching effectiveness.
Attempts have been made as disclosed in U.S. Pat. Nos. 5,360,568, 5,360,569 and 5,370,826 all to Madison et al. to develop a bleach system which is effective in lower temperature water conditions. However, the cationic dihydroisoquinolinium bleach boosting compounds disclosed in these references, when combined with peroxygen compounds, undergo undesired decomposition, causing a reduction in organic catalyst compound efficiency.
U.S. Pat. Nos. 5,576,282 and 5,817,614 both to Miracle et al. disclose a bleach system which is effective in lower temperature water conditions. The zwitterionic dihydroisoquinolinium, organic catalyst compounds, some of which are more or less resistant to decomposition by peroxygen compounds than the cationic dihydroisoquinolinium bleach boosting compounds above, do undergo undesired decomposition, causing a reduction in bleach booster compound efficiency.
Although these references disclose bleaching compositions comprising a bleach boosting compound (cationic dihydroisoquinolinium or zwitterionic dihydroisoquinolinium, which are distinctly different bleach boosting compounds) in the presence of a surfactant (anionic, nonionic, etc.), none of these references recognize or teach a problem with the stability of their respective bleach boosting compounds in the presence of a peroxygen compound, such as a peracid, nor do any of these references teach a synergistic effect between their respective bleach boosting compounds, especially the cationic bleach boosting compounds, and anionic surfactants.
In light of the foregoing, researchers have been trying to develop a bleach system that provides effective bleach boosting compounds, as well as other organic catalyst compounds, such as modified amine compounds, and compositions containing such bleach boosting compounds which provide effective bleaching in lower water temperatures and which exhibit increased stability and resist decomposition in the presence of a peroxygen compound. In other words, the researchers have been trying to develop organic catalyst compounds that exhibit a prolonged effective lifetime.
Accordingly, there remains a need for effective organic catalyst compounds and compositions containing organic catalyst compounds which provide effective bleaching even in lower water temperatures, and resist decomposition by peroxygen compounds.